Cellular immunity plays an important role in the control of immunodeficiency virus infections (P. J. Goulder et al. 1999 AIDS 13:S121). Recently, a DNA vaccine designed to enhance cellular immunity by cytokine augmentation successfully contained a highly virulent immunodeficiency virus challenge (D. H. Barouch et al. 2000 Science 290:486). Another promising approach to raising cellular immunity is DNA priming followed by recombinant poxvirus boosters (H. L. Robinson et al. 2000 AIDS Rev 2:105). This heterologous prime/boost regimen induces 10- to 100-fold higher frequencies of T cells than priming and boosting with DNA or recombinant poxvirus vaccines alone. Previously, investigators showed that boosting a DNA-primed response with a poxvirus was superior to boosting with DNA or protein for the control of a non-pathogenic immunodeficiency virus (H. L. Robinson et al. 1099 Nat Med 5:526). There is a need for the control of a pathogenic immunodeficiency virus.